A driveline disconnect clutch may be used to selectively couple and decouple an engine to a transmission. The driveline disconnect clutch may be positioned in a driveline or powertrain between the engine and an electric machine. If the driveline disconnect clutch is closed quickly, a torque disturbance may be felt by vehicle occupants. One way to close the driveline disconnect clutch may be to request a torque transfer capacity from the driveline disconnect clutch. The torque transfer capacity of the driveline disconnect clutch is an amount of torque that may be transferred by the driveline disconnect clutch. The driveline disconnect clutch torque transfer capacity may be adjusted by changing a pressure of a fluid that applies a pressure or force to close the driveline disconnect clutch. If the application pressure to driveline disconnect clutch torque transfer capacity relationship is incorrect, the driveline disconnect clutch may transfer more or less torque than is requested. Consequently, a driveline torque disturbance may be observed when the driveline disconnect clutch is closed. However, even if the driveline disconnect clutch application pressure to driveline disconnect clutch torque capacity relationship is accurate when the driveline clutch is closing, a driveline torque disturbance may be felt by vehicle occupants because of dynamics related to a time between when the driveline disconnect clutch is commanded to provide a torque capacity and a time when the driveline disconnect clutch is actually able to provide the commanded driveline disconnect clutch torque capacity.
The inventors herein have recognized the above-mentioned issues and have developed a driveline operating method, comprising: requesting adjustment of a driveline disconnect clutch boost time via a controller; applying a pressure to close a driveline disconnect clutch in response to the request; and adjusting the driveline disconnect clutch boost time according to a time between the applying of the pressure and an indication of torque transfer through a driveline disconnect clutch.
By determining and adjusting a driveline disconnect clutch boost time, it may be possible to provide the technical result of compensating for driveline disconnect clutch dynamics so that a desired driveline clutch torque capacity may be provided in a timely manner. In particular, a driveline disconnect clutch boost time may be determined so that compliance between clutch plates may be reduced before torque transfer across the driveline disconnect clutch is desired so that when the driveline disconnect clutch is commanded to transfer a particular amount of torque. The driveline disconnect clutch's torque capacity may then follow the desired or commanded driveline disconnect torque capacity without a delay that may be attributable to removing compliance (e.g., increasing the stiffness of the clutch by removing spacing between clutch plates) within the driveline disconnect clutch. Further, if the driveline is commanded to close to start the engine responsive to vehicle conditions, torque applied to the driveline via driveline torque sources may compensate for the known driveline disconnect clutch boost time by allowing the driveline disconnect clutch boost time to elapse before increasing the ISG torque to start the engine. Alternatively, if the engine is already started and running, adjustments to engine torque may compensate for the driveline disconnect clutch boost time by adjusting engine torque responsive to or after the driveline disconnect boost time elapses. In these ways, torque delivery to the driveline may be timely delivered so that there may be less possibility of driveline torque disturbances.
The present description may provide several advantages. For example, the approach may provide improved vehicle noise, vibration, and harshness. Further, the approach may reduce degradation of driveline components. Additionally, the approach may improve driveline disconnect clutch control.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.